Borosilicate vs Soft Glass vs Silicone vs Steel
Filtration devices and vapor paths are built from a handful of base materials. Each one has real tradeoffs in heat resistance, durability, taste neutrality, and cleaning. Here is what you actually need to know.
Borosilicate glass
Borosilicate (boro) glass is the gold standard for filtration hardware. It contains boron trioxide, which gives it an extremely low coefficient of thermal expansion—meaning it can handle rapid temperature changes without cracking. It is chemically inert, meaning it does not leach anything into the vapor path, and it is easy to clean with isopropyl alcohol.
- Thermal shock resistance: Can handle ~500°F swings without fracturing
- Taste: Completely neutral—adds nothing to the flavor
- Cleaning: Isopropyl soak, salt shake, rinse. Transparent so you can see buildup.
- Downsides: Brittle on impact. Drop it on tile and it shatters.
Brands in our catalog using borosilicate: NWTN Home, Human Grade, Storz & Bickel (mouthpieces and bubblers).
Soft glass (soda-lime)
Soft glass is the most common type of glass in the world. It is cheaper and easier to work at lower temperatures, which allows artisan glassblowers to create elaborate, colorful designs. However, it has a higher thermal expansion coefficient than boro, making it more prone to cracking from rapid heat changes.
- Workability: Easier to blow into complex shapes and colors
- Taste: Neutral when clean
- Cleaning: Same as boro, but thicker walls mean slower heating/cooling
- Downsides: Less thermal shock resistant, heavier, can contain trace impurities depending on manufacturer
Softglass in our catalog uses verified soda-lime formulations from established manufacturers.
Silicone
Silicone filtration devices are nearly indestructible—you can fold them, drop them, and throw them in a bag. But not all silicone is equal. Only platinum-cured, USP Class VI or FDA food-grade silicone should be anywhere near heated vapor. Cheap silicone from unknown sources can contain plasticizers that off-gas at elevated temperatures.
- Durability: Virtually unbreakable
- Taste: Slight taste compared to glass, especially when new
- Cleaning: Dishwasher safe, but harder to see residue buildup
- Downsides: Can absorb odors over time. Must verify the grade—no grade, no trust.
Stainless steel
316L surgical stainless steel is used in condenser tubes, downstems, screens, and structural components of high-end devices. It is the same alloy used in surgical implants and food processing equipment.
- Durability: Extremely tough, corrosion-resistant
- Taste: Minimal—less neutral than glass but far better than other metals
- Cleaning: ISO soak, ultrasonic cleaner, or boiling
- Downsides: Opaque—cannot see internal buildup. Must confirm 316L grade, not generic “stainless.”
Quick comparison
| Factor | Borosilicate | Soft Glass | Silicone | 316L Steel |
|---|---|---|---|---|
| Heat resistance | Excellent | Good | Good (to ~450°F) | Excellent |
| Impact resistance | Low | Low | Excellent | Excellent |
| Taste neutrality | Best | Great | Good | Good |
| Cleaning ease | Best | Great | Good | Great |
| Cost | Mid–High | Low–Mid | Low | Mid–High |